Abbreviations used herein:
TDMTime Division MultiplexingATMAsynchronous Transfer ModeIPInternet ProtocolDSPDigital Signal ProcessorLBLoad BalancingBFBest FitFCPFirst Channel PenaltyCCDClear Channel Codec
A voice gateway is an example of the type of device that must assign tasks to resources. Voice gateways are devices that convert voice TDM signals to packets. Voice gateways receive information from call agents. Call agents setup voice and data calls on the voice gateways. A voice gateway converts TDM signals in the incoming call to IP packets in one direction and it does the opposite in the reverse direction. The call agents communicate with the voice gateway using a protocol such as MGCP or H.248 typically over an IP network. The call agent generally provides the voice gateway with information concerning which codec should be used for each particular call. Voice gateways and call agents are in widespread use.
Voice gateways typically include a plurality of DSPs. The DSPs are programmed to terminate TDM voice calls and convert the raw voice data into IP or ATM packets. The DSPs converts each call using the particular codec specified by the call agent. One DSP can generally handle a plurality of voice channels and a voice gateway generally includes a number of DSPs. The amount of resources used by a DSP to handle a particular call depends upon the codec specified for that call. For optimum operation it is desirable to assign calls to the various DSPs such that the DSPs in the unit are equally loaded; however, there are also other considerations that can be taken into account when assigning resources to calls.
In the prior art a number of different techniques have been used to assign calls to DSPs in a voice gateway. In one technique the available capacity of each DSP is tracked and when a new call arrives, a search is made through a series of data structures to find a channel for the incoming call. Ideally an algorithm should perform suitably under a variety of conditions such as under both high and low load conditions.